Tips to Care for Hydrangea

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 Exactly what do you need to do now to finish pruning of old wood flowering hydrangeas (big leaf, mountain, oak leaf, and climbing)? Yes, you need to see “broccoli” before taking your final cuts. But at least now, you can freely dead head (remove spent flowers) and clean up your plants, even the rebloomers. 

Besides pruning at the wrong time, hydrangeas don't bloom because they didn't get enough sun or fertilizer, or an early frost or cold spell killed the buds. It's OK to deadhead spent hydrangea heads in the summer; it will not harm the plant. Deadheading and pruning (removing more than just the flower head) hydrangeas are two different techniques..

• If in doubt, don’t prune. Hydrangeas don’t need pruning to stay healthy.
• If you need to prune and don’t know when the best time is for your type of Hydrangea, do it immediately after the bush has stopped flowering.
• If you did happen to prune your Hydrangea at the wrong time, they will be back better than ever the following season.

Deadhead Spent Flowers

• During the growing season, you can deadhead the flowers (remove spent flowers) as they fade.
• Pruning helps prolong the bloom season as the plant puts more energy into continued blooming.

 Panicle (perigee) hydrangeas (H. paniculata) have large cone-shaped flower panicles. The flowers are white or green when they first bloom, gradually turning pink. This type is another hydrangea that flowers on new wood, requiring late winter or early spring pruning. 

Once you have made all your cuts, take the time to fertilize your plants with a granular fertilizer that is labeled for shrubs. Rose fertilizer is ideal.

Rose-tone fertilizer is an excellent product for hydrangea health

Stay away from 10-10-10 as no plant uses nutrients in the same amounts and all those products do is contribute to pollution and runoff. You could also add compost but don’t fool yourself into thinking it is a substitute for fertilizer.

Pruning your big leaf and mountain hydrangeas can be as simple as deadheading all the old flowers. Period. But you might also take the time to remove any diseased, damaged, and dead wood. Consider going further down the plant – carefully – to remove the leftover dead stubs from prior year’s cuts. This is where the reciprocating saw really works well.

Look for branches that are crossing or rubbing with another, and any that are growing toward the inside of the plant. I would also encourage you to remove any stems thinner than a pencil as they will not produce a flower. Those skinny stems will rob your plant of the energy it needs for the stronger stems.

 Bigleaf hydrangeas bloom on old wood, setting their flower buds from late summer to early fall. If you mistakenly prune in the spring or even late fall, it will remove the flower buds and any chance of getting blooms for a year. 

 Bigleaf hydrangeas do pretty well without any pruning, but if necessary, to control their shape or size, prune them carefully just after the flowers have faded, never removing more than one-third of their total growth. 

 The reason you needed to wait is that if you removed – even just deadheaded – rebloomers prematurely, you would have stimulated their “sleeping buds” to initiate growth. Those new growth/buds could have been zapped by a late season freeze. Now thanks to the wonder of technology, you are assured that the buds you will stimulate will not be affected by damaging cold temps. Of course, you will still need a forgiving summer to get the later season flowers from your rebloomers. The best you can do for them is fertilize and irrigate properly as the season progresses. 

 Smooth (wild) hydrangeas (H. arborescens) have big and round spring and early summer flowers, either white or shades of pink. The most common garden variety is 'Annabelle,' easily identified by its huge snowball-shaped flowers. This plant flowers on new wood, so you'll prune it in late winter or early spring.